Currently, optical parametric chirped-pulse amplification (OPCPA) has become an effective technique for generating ultrashort pulses with ultrahigh peak-powers. The basic principles of OPCPA includes the following three steps:
first, pulse broadening, that is, ultrashort pulses are stretched to chirped pulses by a grating stretcher;
second, pulse amplification, that is, the chirped signal pulses are amplified in parametric amplifiers, where the energy of the pump pulse flows into the chirped signal pulse and an idler pulse is generated simultaneously; and
third, pulse compression, that is, the amplified chirped pulses are compressed back to the original pulse duration to generate ultrashort intense pulses with a grating compressor.
Because of its satisfactory characteristics of high-efficiency, large amplified bandwidth and wavelength tunability, OPCPA may be employed to generate high-power, few-cycle pulses from visible to mid-infrared spectral region. In fact, the peak power of the ultrashort pulse has already reached petawatt level by OPCPA. However, high average-power OPCPA remains a bottleneck problem in the field of laser technology. Because of the absorption of the laser energy, thermal effects becomes the dominating problem that limits the average-power scaling in OPCPA. The reason is that the nonuniform temperature distribution destroys the key phase-matching (PM) condition, which leads to the drop in the efficiency and deterioration of pulse characteristics in the amplifiers. Currently, the average power in OPCPA is still limited to 100 W, which is far less than desired power level for revolutionizing the ultrafast science.
Currently, the solutions to high average-power OPCPA amplifier mainly focus on improving the heat dissipation ability. However, the inherent problem of thermally-induced phase-mismatch cannot be resolved with these solutions. In fact, temperature-insensitive PM is the prerequisite for high average-power OPCPA amplifier. Nevertheless, the main difficulty is the lack of the control parameter in manipulating the PM. In our previous work (U.S. Pat. No. 9,711,931), we have realized simultaneous temperature- and wavelength-insensitive PM with the two control parameters of noncollinear configuration and angular dispersion, which may be used to produce ultrashort pulses with both high peak powers and high average powers.